This invention relates to a sprung castor wheel assembly of the type including a base member for attachment to an object to be supported, a swivel member mounted on the base member for rotation about a vertical swivel axis, a wheel mounted on the swivel member for rotation about a horizontal axis offset to one side of the vertical swivel axis and spring suspension means between the wheel and the swivel member to allow some flexing of the wheel in a vertical direction in response to impact with uneven terrain, curbs or the like.
Sprung castor wheel assemblies of the above type are well known and are used on many different types of equipment for supporting the equipment in movement across the ground. One particular area where castor wheels of this type are used is in relation to pallet lifting dollies. Such pallet dollies include a pair of parallel lifting bars each having a ground wheel at an outer end thereof. At an inner end of the bars is provided a main support structure with a manual control unit, the main supporting structure including a main central wheel acting as drive and steering wheel in what is essentially a three wheeled unit. In order to prevent tilting of the main unit to each side there is provided a pair of castor wheels one on each side of the main drive wheel. These castor wheels are sprung so the wheel can lift slightly to accommodate uneven terrain or impact with curbs or the like. However one prior construction is relatively complex and expensive and also is prone to damage since the main side plates supporting the wheels are not sprung and if they should impact a curb, the full impact is taken within the swivel joint often causing damage.